1. Field of the Invention
This invention relates to the operation of an internal combustion engine employing a pre-engine catalytic reformer for upgrading the octane number of the fuel.
2. Background Information
Pre-engine converters utilizing catalysts comprising intermediate pore zeolites for improving the octane number of fuels utilized in internal combustion engines are known in the art as shown in the Information Disclosure Statement set out hereinafter. However such catalysts generally rely for their effect on a substantial degree of acidic cracking activity. They are not particularly effective for catalyzing reactions more prevalent in a reforming than a cracking process, e.g., dehydrogenation and dehydrocyclization such as are utilized for the conversion of n-paraffins to aromatics in the presence of cycloparaffins. In many instances, the latter reactions are more effective in raising the octane number of a low octane chargestock than primarily cracking reactions, particularly in the synthesis of aromatics which are especially significant in obtaining higher octane numbers of gasolines.
There are many primarily reforming catalysts known in the art which are suitable for use in a refinery for the purpose of upgrading the octane number of refinery streams intended as gasoline blending components. However, these catalysts have usually not been suggested for use in a pre-engine converter, and, in fact, conventional reforming catalysts, such as those comprising platinum supported on alumina, deactivate fairly rapidly under the conditions preferred for the operation of a pre-engine converter, e.g., the absence of added hydrogen and the use of relatively low absolute pressure. These conditions are unlike those usually employed in a refinery which generally include, for example, hydrogen addition and the employment of higher absolute pressures. Other reforming catalysts disclosed i the art, e.g., comprising a Group VIII metal and a non- or low-acid intermediate pore zeolite, are also generally intended to be used with hydrogen in a refinery reforming process.